Designing of calendars has a very broad and rich achievement. The primary task of calendars is to inform about passing time. However, a calendar can be used in various distinctive ways and therefore there is so many unique designs of the calendar.
An appearance and a structure of calendars has been determined by numerous factors, being taken for consideration, during the entire designing process. For example, where the usefulness of the calendar was considered as a priority, the design process brought forth all kinds of pocket and planner calendars. Many other designs aspired to give a calendar an original appearance and attractive aesthetic look. A good example of such design is a very popular illustrated calendar. Furthermore, to make calendar more entertaining the illustrations become designed as a numerous type of cross-word puzzles, humors, etc. . . . Unfortunately, that type of entertaining gains personally and timely limited interest. Boes in his patent teaches a calendar comprising a top as a removable sheet and a lower sheet which carries a picture, all included within a frame, to activate the continues entertaining and interest in the calendar. While such a design activates continues personal participation, it still results in limited type of entertaining, which generally procures a gradual exposing of underlaying picture.